Experimental study on cutting force in shear thickening polishing of hardened bearing steel

Shear thickening polishing (STP) is a finishing process that uses an non-Newtonian abrasive slurry to remove workpiece material. This method is used to polish the complex surfaces with a simple machining process. In this process, the polishing force are important factors that affect the surface roughness of workpiece. Polishing parameters are determined based on the Taguchi experimental design method. In addition, the analysis of variance (ANOVA) and regression analysis were also carried out. The polishing speed (60, 65, 70 and 75 rpm), working gap (15, 20,25 and 30 mm) and abrasive concentration (20, 25, 30 and 35 wt%) were chosen as machining parameters. In the ANOVA analysis, it was determined that the most effective parameters on force Fx/Fy/Fz values were working gap (92.86%/85.07%/90.51%), polishing speed (3.27%/11.43%/4.47%) and abrasive concentration (0.01%/0.03%/0.05%), respectively. The optimum parameter for maximum polishing force were found to be polishing speed of 75 rpm, working gap of 15 mm, and abrasive concentration of 35%. Under the optimal polishing parameter, an experimental model of STP for inner ring of angular contact spherical plain bearings has been conducted. As a result, the surface roughness Ra/Rz of inner ring is reduced from 0.08/0.53 to 0.02/0.13 μm. It was achieved about 75%/76% better. Comparing with the non-optimal STP process, the surface roughness Ra/Rz was upgraded 60%/58%. Experimental results demonstrate that the surface quality of the workpiece is significantly improved under suitable cutting force conditions.